Sheet feeding device



ma ma H. KRATZ April 11, 1933.

SHEET FEEDING DEVICE Filed Oct. 25, 1931 5 Sheets-Sheet H. KRATZ ET FEEDING DEVIC SHE 5 Sheets-Sheet Filed Oct.

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SHEET FEEDING DEVI CE Filed Oct. 25, 1931 3 Sheets-Sheet 3nnentor attorney tzpe with means Patented Apr. 1i,

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Ell? sense DEVICE application filed @etoher as, 1931. serial 23o. Wealth.

The invention relates to new and useiul improvements in sheet ieeding devices, and more particularly to devices for feeding metal sheets one at a time from a stack or ile.

An object sheet feeding mechanism with a sheet separating device which engages the forward edge portion of the sheet, retracts and lifts the same for freeing said sheet from the sheets beneath prior to the feeding of the sheet.

A. further object of the invention is to rovide a sheet separating device of the for vibrating the same after e'sheet has been lifted from the stack for insuring the release of the suction lift of said sheet on the underlying sheet.

These and other oh ects will in part he obvious and will in part he hereinafter more fully disclosed.

in the drawings which show way of illustration one embodiment of inven tion- I i v Figure 1 is a side view of a portion of a sheet feeding mechanism embodying the innprovements;

Fig. 2 machineto which plied; I

Fig. 3 is a view partly in section and part ly in side elevation showing the sheet litting mechanism, the feeding mechanism and the separating mechanism;

Fig. 4 is a detail showin rating device and the cam same;

Fig and the suction pi is a plan view of a portion of the the improvements are ap the sheet sepaor operating the 5 is a detail showing the control valve es leading therefrom to the lifting cups an the separating cup;

Fig. 6 is a detail in vertical section of the se iarating cup, and

ig. 7 is a diagrammatic view showing the sheet retracted and lifted so as to unlock it from a hook on the underlying sheet.

The invention is shown as applied to an automatic stack'liftin'g and sheet feeding device such as disclosed in the patent to Henry A. Fink #1,695,233, granted December 11, In the operation of this sheet of the invention is to provide a be retracted so as is mounted a sheet supporting feeding mechanism the rear portion or? the topmost sheet is hit/ed by suction cups into the nth of reciprocation of a feed or whic engu es the rear, edge of the sheet and feeds t e sheet forward into the machine. The machine is particularly adapted for use in connection with a sheet slider, but it may he used for other urposee. It sometimes occurs that in handling s sheets, the. ed es of the sheets become bruised, forming hoo which so look two sheets togather, that one will carry the other along when it is ted from the stack. The pnt invention has to do with. a sheet separating device which works in conjunction with the sheet lifting and feeding mechanism, as shown in this Fink patent. This sheet separating device is in the form of a suction cup carried hy a swinging lever operated by a cam so that the cup is moved down into contact with the sheet adjacent the forward edge thereof, and i raised, it will cause the sheet to buckle and any hook formed on the underlyinv sheet. The separating device after it reac es the upper end of its movement and has freed the sheet from the underlying sheet, is given a vibration for the purpose of breahng any suction lift between the raised sheet and the underlying sheet, thus insuring that the front edge rtion of only one sheet is liited. After the s set has been thus separated, the suction cups adjacent the rear edge of thesheet will raise said portion so that the feeding device will engage said rear portionand convey the sheet away from the stack and into the mechanism which is to operate on is so time as-to bring about the lifting of the sheet inthe manner described releasing of the move the same forward. v

The invention will be better understood by a detail description of the present illustrated embodiment thereof. The machine in general includes a main frame 1 on whichdevice 2. The agrammaticalstacked sheets are indicated 1y at in Fig. 1 of the drawings.

when this suction cup is to unlock the same from the sheet. The "suction cu s are controlled by a valve which and the sheet for the feed finger to l stack lifting and feeding mechanism is shown as used in connection with a slitter, the frame of which is indicated in broken lines at The sheet lifting mechanism is provided with automatic means for maintaining the top of the stack at a predetermined level, that is,

on a level with the table or sup art 4 over which the sheets are fed into the s itter. The sheets are lifted from the stock by suction cups 5, 5, only one of which is shown in the drawings. 'lhe suction cup is carried by a rod 6 which is attached to a slide.7 carrying a roller 8 bearing on a lift cam 9. There are two lift cams, one for each suction cup. These lift cams are mounted on a shaft 10 which is rotated by suitable driving mechmism. Each suction cup 5 is connected to a pipe 11. These pipes are in turn connected to a control valve 12 which controls the suction .on the cup 5. The valve is so timed as to place a suction on the cup for the lifting of the sheet, and the sheet is released from the suction cup when the feeding device has been positioned so as to raise the sheet. The lift cams for the suction cups 5 are shaped as clearly shown in the drawings so as to lift the cups quickl holding the on in raised position for as ort time to enab e the sheet to be fed from underneath the cu after which it is lowered on to the stack. The lift cam is provided with a short radially extended portion 9 which gives a slight lift to the suction cup, releasmg the same for the purpose of lifting the sheet to break the suction grip betweenthe topmost sheet and the underlyin sheet. The sheets are fed from the stac by a feeding device in the form of-a feed finger 13. This feeding finger 13 is carried by a crosshead l which is mounted for reciprocation on a supporting rail 15. The crosshead 14= has depending lugs 16 between which is placed a link 1'? which is pivoted to the lugs by a pivot pin 18. The

ger 13 is mounted on the link 17 and thus is supported by the crosshead 1 4. rho other end of the link 17 is pivoted at 19 to a swinging arm 20. The arm 20 is, pivoted at 21 to a bracket 22 carried by the frame of the machine. An eccentric strap 23 is pivoted at 24 to the arm 20 and cooperates with an eccentric 25 on the shaft 10. As the shaft 10 rotates, the eccentric will oscillate the arm 20 and this causes the crosshead 14 to move back and forth from the full line position shown in Fi 3 to the broken line.

position shown therein. This is the length of feed stroke of the finger, and by this movement' the sheet is fed forward so as to he engaged b a conveying device which conveys the s eet through the mechanism operating upon the same.

Mounted on a. bracket 26 is a presser foot member 27. There are two presser feet which are located at opposite sides of the suction cups and the feeding device. The suction cups are comparatively close to the feeding device, and the purpose of these resscr feet is to cause the sheet to be buckle at the center thereof for the purpose of releasin any auction grip of the sheet on the under ying sheet. his insures that only one sheet will be lifted by the suction cups and placed in position for the feeding device to move the sheet forward.

The machine thus referred to is substantially the same as shown and described in the Fink patent, and further detail description thereof is not thought necessary.

It often occurs during the handling of a stack of sheets that the edges will be knocked and bruised so as to turn the edge on the sheet forming a hook so that it is locked to the sheet next above. In such cases, when a sheet is fed from the stack, it carries along with it the underlying sheet, thus feeding two sheets at a time into the operating mechnism, which injures the sheets or the parts of the machine operating thereon. The prcsent invention, as noted above, is directed to a means for unlocking an hooked edges so as to insure the feeding 0 only one sheet at a time. This is accomplished by the separating mechanism which separates the uppermost sheet from the next sheet underlying the same. This separating mechanism includes a suction cup 28 which is preferably larger in diameter than the suction cup 5. The sucti 11 cup is shown in detail in Fig. 6, and inclu es a rubber cup secured to a shank 2'9 which is pivoted at 30 to a lever 31. Said lever 31 has a series of openings 32 therein so that the ivot pin supporting the cup may be shifted rom one osition to another for difierent'widths of s eets. The suction cup is placed under vacuum by a flexible pipe 34 leading to the valve 12. The valve 12 is timed so as to create a suction within the cup 28, so as to cause said cup to grip a sheet when pressed against the same and lift the sheet with the cup. The lever 31, as clearly shown in F i 3 of the drawin is pivoted at 35 to a bradket arm 36 attached to the frame of the machine. Said lever 31 carries a roller 37 hearing against a cam 38 on the shaft 10. The cam 38 is provided with a concentric portion 39, a cutaway radial portion 40 and a cam radial portion 41. There is also formed in the concentric portion 39 a series of reverse curved sections 42, 42. The cam 38 turns in the direction of the arrow as shown in Fig. 3. When the cam is in the position shown in this figure, the cup is in its lowered position and is in contact with the sheet. It will grip the sheet firmly, so that when the cup is raised, the sheet will be lifted therewith. The pivotal point 30 between the lever and the cup is at a considerable distance below the fu crum point 35 where the lever is supported, and therefore, as the lever'is depressed at the left-hand end in Fig. 3, it will be raised Ill at the right-hand end, and the pivotal point will move away from the fulcrum int to aslight extent. The cup, however, in

pivoted tothe lever, will swing inward, an

the resulting action isa buckling of the sheet, as shown in Fig. 7. Thesheet is not only buckled, but is retracted at the advance edge thereof, indicated at a in the -drawings, and this "operates to release said advance ed e from the hook on the advance edge of the underlying sheet, which is indicated at b. When the cup, which is lifted quickly, reaches the upper end of its stroke, it remains in the raised position as the cam 38 continues to rotate, and as the roller passes overthe curves or depressions t2, the cup will he vibrated up and down, and this will tend to shake loose any sheet clinging to the under face of the uppermost sheet, due to the suction lift of vacuum pockets in thesheet.

In the operation of the machine, the separating device engages the topmost sheet,unhooks the ends, it they are interlocked, and lifts the forward or advance ed e of the sheet, shaking it loose from the un er sheet, and while this is takin place, the suction on s 5 are in contact with the sheet, holding t e sheet down onthe stack. When the surface 9* of the cam 9 contacts with the roller 8, it

will then lift the suction cups 5 and the sheet will be raised into position for the feed finger 13 to engage the rear edge or the sheet and move it forward into the mechanism which operates upon the sheet. The cam'38 lifts the suction cup 28, and the spring 43 holds the lever 34 in contact with the cam and forces the cup downward into contact with the sheets as the control cam releases the same. When the suction is released on the cup 28, then the sheet will he released and it will straighten out. This occurs practically simultaneously with the release of the sheet from the suction cups 5, preliminary to the feeding of the sheet by the forward movement of the feed finger, and therefore, the sheet will be fed from the stack without again being hooked so as to carry with it the underlying sheet.

While the sheet separating device is shown 7 as used in connection with the automatic stack raising mechanism and sheet feeding device of the Fink patent, it will he understood, of course, that it is adapted for use with other types of stack raising and sheet feeding devices. It will also he understood that the details of construction and the arrangement of the parts may be varied without departin from the spirit of the invention as set fort in the appended claims.

Having thus described the invention, what I claim as new and desire to secure by Letters Patent, is'

1. A sheet feeding mechanism comprising a support for the stacked sheets, a reciproeating feeding device engaging the rear edge of the sheet for feeding the same from the stack, meam, for lifting the rear portion of the ,I H sheet from the stack for permitting I engagement of the feeding device therewith, and means adapted to engage the topmost sheet adjacent the forward edge thereof for retractin and lift the torward edge portion 0 said sheet or freeing the same from the stacked sheets prior to the engagement of the feeding device with the sheet for the movement of the same from the stack.

2. A sheet feeding mechanism comprising a su portfor the stacked sheets, a reciprocating ceding device en aging the rear edge of the sheet for feeding e same from the stack, means for lifting the rear ortion of the to most sheet from the stack or permittingt e engagement of the feeding device therewith, a suction cup adapted to engage the to most sheet adjacent the forward edge thereo and means operating to raise the suction cup and tilt the same so as to retract and lift the forward edge portion oi the sheet for freeing the same from the stacked sheets prior to the engagement of the feeding device with the sheet for the movement of the same from the stack. 4

3. in sheet feeding mechanism comprising a support for stacked sheets, a feeding device enga ing the rear edge of the sheet for feeding the same from the stack, means for lifting the rear portion of a sheet from the stack for engagement by the feeding device, a lever pivotally supported for oscillation on an axis in rear of the advance edge of the sheet, a suction cup pivoted to the end of the lever and adapted to engage the topmost sheet adjacent its front edge, and a cam for oscillating said lever for retracting and lifting the forward edge of the sheet prior to the lifting oi the rear portion of the sheet for engagementh the feedin device.

a. A sheet teeding mechanism comprising a support for stacked sheets, a feeding device enga ing the rear edge of the sheet for feed ing t e same from the stack, means for litting the rear portion of a sheet from the stack for en agement by the feeding device, a lever pivota ly supported for oscillation on an axis in rear of the advance edge of the sheet, a suction cup pivoted to the end of the lever and adapted to en age the topmost sheet 5. A sheet feeding mechanism comprising i a support for stacked sheets, a feeding device cnga mg the rear edge of the sheet for feeding t e same from the stack, means for lift- 4- gimme ing the rear poniun of as sheet. 51mm film smck for engagement by the feed 7 dsvifie k ver pivobally an ports fin mmllmzian w an axis in rear of i, e advance edge 0% the sham a suction eu pivoted to the and? ark the lava? v and adagte t0 en age ihe mpmosiz eheefa adjacemfis r s from a ge, cam esefliatingg sfiiri have? far iifiimgg the cup for oscifimfiing (Jim 16%;: under eem'lzmi 01" @h@ w cam fmwwingg 52m map, whemby Elbe sheets engmgai the) eug: is mtmsfia-zi and ed prim 5m 5m iifisimg m 1 3516 the sheaf; far engiagomsmz b dsvise.

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